Excessive lead levels found in almost 2,000 water systems across the states, including North Carolina.

While a harsh national spotlight focuses on the drinking water crisis in Flint, Michigan, a USA TODAY NETWORK investigation has identified almost 2,000 additional water systems spanning all 50 states where testing has shown excessive levels of lead contamination over the past four years.

The water systems, which reported lead levels exceeding Environmental Protection Agency standards, collectively supply water to 6 million people. About 350 of those systems provide drinking water to schools or day cares. The USA TODAY NETWORK investigation also found that at least 180 of the water systems failed to notify consumers about the high lead levels as federal rules require.

Many of the highest reported lead levels were found at schools and day cares. A water sample at a Maine elementary school was 42 times higher than the EPA limit of 15 parts per billion, while a Pennsylvania preschool was 14 times higher, records show. At an elementary school in Ithaca, N.Y., one sample tested this year at a stunning 5,000 ppb of lead, the EPA’s threshold for “hazardous waste.”

"This is most definitely a problem that needs emergent care," Melissa Hoffman, a parent in Ithaca, forcefully pleaded with officials at a public hearing packed with upset parents demanding answers.

In all, the USA TODAY NETWORK analysis of EPA enforcement data identified 600 water systems in which tests at some taps showed lead levels topping 40 parts per billion (ppb), which is more than double the EPA's action level limit. While experts caution Flint is an extreme case of pervasive contamination, those lead levels rival the 400-plus of the worst samples in far more extensive testing of around 15,000 taps across Flint. The 40 ppb mark also stands as a threshold that the EPA once labeled on its website an “imminent” health threat for pregnant women and young children.

Even at small doses, lead poses a health threat, especially for pregnant women and young children. Lead can damage growing brains and cause reduced IQs, attention disorders, and other problem behaviors. Infants fed formula made with contaminated tap water face significant risk. Adults are not immune, with evidence linking lead exposure to kidney problems, high blood pressure, and increased risks of cardiovascular deaths. The EPA stresses there is no safe level of lead exposure.